Effect of doped titanium on microstructure of UO2 microspheres

This paper studies the effect of 0.7% of doped titanium on the microstructure of UO2 microspheres. The results show that the increasing of the sintering temperature reduces the number of pores, but the volume of each single pore increases instead, which might be due to a fusion between the small pores. In the presence of the doped titanium, the growth rates of grain are inconsistent at a temperature of 1250℃ to 1450℃. Some grains begin to grow rapidly and the distribution of grain sizes shows a 'double high' characteristics. However, at the temperature of 1550℃. the grain sizes are distributed in a normal way with the average grain size of about 42 μm. At the temperature of 1250℃ to 1450℃, UO2 microspheres with doped titanium are sintered with the majority of titanium dioxide uniformly distributed inside the grains in the microspheres and a small amount of titanium dioxide enriching in the grain boundary. While at the sintering temperature of 1550℃, titanium dioxide is most enriched in the grain boundary. (authors)